text: One of the most commonly quoted potential causes of WECs is hydrogen embrittlement caused by an unstable equilibrium between material, mechanical, and chemical aspects, which occurs when hydrogen atoms diffuse into the bearing steel, causing micro-cracks to form. Hydrogen can come from a variety of sources, including the hydrocarbon lubricant or water contamination, and it is often used in laboratory tests to reproduce WECs. Mechanisms behind the generation of hydrogen from lubricants was attributed to three primary factors contributing: decomposition of lubricants through catalytic reactions with a fresh metal surface, breakage of molecular chains within the lubricant due to shear on the sliding surface, and thermal decomposition of lubricants caused by heat generation during sliding. Hydrogen generation is influenced by lubricity, wear width, and the catalytic reaction of a fresh metal surface.